Implantable electrical stimulators may be used to deliver electrical stimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. In general, an implantable stimulator delivers electrical stimulation therapy in the form of electrical pulses. An implantable stimulator may deliver electrical stimulation therapy via one or more leads carrying electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the stomach of a patient. Hence, stimulation may be used in different therapeutic applications, such as deep brain stimulation (DBS), spinal cord stimulation (SCS), pelvic stimulation, gastric stimulation, or peripheral nerve stimulation. Stimulation also may be used for muscle stimulation, e.g., functional electrical stimulation (FES) to promote muscle movement or prevent atrophy.
A clinician selects values for a number of programmable parameters in order to define the electrical stimulation therapy to be delivered by the implantable stimulator to a patient. For example, the clinician ordinarily selects a combination of electrodes carried by one or more implantable leads, and assigns polarities to the selected electrodes. In addition, the clinician selects an amplitude, which may be a current or voltage amplitude, a pulse width and a pulse rate for stimulation pulses to be delivered to the patient. A group of parameters, including electrode combination, electrode polarity, amplitude, pulse width and pulse rate, may be referred to as a program in the sense that they control the electrical stimulation therapy delivered to the patient. In some applications, an implantable stimulator may deliver stimulation therapy according to multiple programs either simultaneously or on a time-interleaved, overlapping or non-overlapping, basis.
The process of selecting a program can be time consuming. The clinician typically will evaluate a variety of electrode combinations, polarities and parameter values to identify an acceptable program. The clinician selects a program that balances effectiveness of the therapy in relieving symptoms with the presence of undesirable side effects. In addition, to some extent, efficacy may be rated in terms of the amount of power consumed by a program. For example, among programs providing equivalent effectiveness and side effects, programs that tend to conserve power may be considered superior. To achieve an acceptable level of efficacy, a clinician must evaluate various stimulation parameters and accurately track results.